By Justin Jacques

Johnston Atoll National Wildlife Refuge – part of Pacific Remote Islands Marine National Monument – is remote indeed.

The refuge is surrounded by a 400-mile- wide circle of marine conservation – co-managed by the U.S. Fish and Wildlife Service and the National Atmospheric and Oceanic Administration – in which commercial fishing is prohibited. The refuge is a three-day boat trip from Honolulu. Before 2010, staff members made trips to Johnston Atoll only every two to three years. On one such trip, refuge biologists found that Johnston Island, the 50-square-mile atoll’s largest land mass, was infested with invasive yellow crazy ants.

Since 2010, groups of volunteer biologists called Crazy Ant Strike Teams (CASTs) have made great progress in controlling the ants, which are a menace to Johnston Atoll Refuge seabirds, including what is likely the world’s largest red-tailed tropicbird colony.

Once yellow crazy ants arrive in an isolated place like Johnston Atoll – usually by boat or driftwood – they expand their territory by forming super- colonies around hundreds of queens, not just one. The ants overwhelm indigenous wildlife by spraying corrosive acid. Red-tailed tropicbirds suffer burns to their beaks, feet and eyes. The ants often overrun nests and force tropicbirds to sea.

In 2010, with no natural predators present, yellow crazy ants had occupied one-fifth of Johnston Island. Since then, 10 CASTs have spent six months each experimenting with baits and insecticides to develop an effective formulation. During CAST 3’s stint in 2011-2012, yellow crazy ant numbers dropped by 99 percent.

“One day there were carpets of ants crawling across roads, and within 48 hours it was difficult to find a single ant, unless you were looking really hard for one,” says Stefan Kropidlowski, the CAST field operations and logistics manager.

In 2014, Johnston Atoll Refuge received the National Wildlife Refuge System’s $1 million Large Invasive Species Project Allocation, which funded strike teams for two more years.

The allocation funded an agreement with the U.S. Geological Survey to generate new eradication methods. CAST 10, currently on the island, is the first team to use a technique developed with USGS support. It mixes effective pesticides with sugar. The solution is absorbed into polyacrylamide crystals, and the resulting bait is distributed to ants by hand.

“CAST 10 results have been promising, with another 99 percent yellow crazy ant decline in all treated areas,” says Kropidlowski. “Only time will tell if this new method will be the magic bullet to nail that last 1 percent and eradicate yellow crazy ants from Johnston Atoll.”

Being a CAST member takes grit. “There’s no freshwater source or plumbing on Johnston, no indoor toilets, and no option for bathing or doing laundry other than the ocean, where sharks are a given,” July/August 2015 Audubon magazine noted. Team members, often entry-level biologists, undergo a rigorous evaluation process before deployment to Johnston Atoll.

In 2010, Kropidlowski and CAST 1 estimated that 12 red-tailed tropicbird nests existed in Johnston Atoll’s infested areas. After CAST 3’s work in 2011-2012, a two-week census counted 5,756 active red-tailed tropicbird nests across the island, 80 in the infestation area.

“Tropicbirds nest year-round, so the actual number will be even higher,” says Amanda Pollock, deputy superintendent of the Pacific marine national monuments and CAST project leader. “There are an estimated 32,000 red-tailed tropicbirds in the global population. If that is the case, then it is possible that 36 percent of the world’s population was breeding on Johnston Island in just that two- week period in which the census was conducted.”

Justin Jacques is a senior at George Washington University in Washington, DC.